/**
 *  CHECKER1.c -- Mouse Hit-Test Demo Program No. 1
 *          (c) Charles Petzold, 1998
 */

#include <windows.h>

#define DIVISION 5

LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
    static TCHAR szAppName[] = TEXT("Checker1");
    HWND hwnd;
    MSG msg;
    WNDCLASS wndclass;

    wndclass.style = CS_HREDRAW | CS_VREDRAW;
    wndclass.lpfnWndProc = WndProc;
    wndclass.cbClsExtra = 0;
    wndclass.cbWndExtra = 0;
    wndclass.hInstance = hInstance;
    wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wndclass.hCursor = LoadCursor(NULL, IDC_ARROW);
    wndclass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
    wndclass.lpszMenuName = NULL;
    wndclass.lpszClassName = szAppName;

    if (!RegisterClass(&wndclass))
    {
        MessageBox(NULL, TEXT("This program requires Windows NT!"), szAppName, MB_ICONERROR);
        return 0;
    }

    hwnd = CreateWindow(szAppName,
                        TEXT("Checker1 Mouse Hit-Test Demo"),
                        WS_OVERLAPPEDWINDOW,
                        CW_USEDEFAULT,
                        CW_USEDEFAULT,
                        800,
                        800,
                        NULL,
                        NULL,
                        hInstance,
                        NULL);
    ShowWindow(hwnd, iCmdShow);
    UpdateWindow(hwnd);

    while (GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    static BOOL fState[DIVISION][DIVISION];
    static int cxBlock, cyBlock;
    HDC hdc;
    int x, y;
    PAINTSTRUCT ps;
    RECT rect;

    switch (message)
    {
    case WM_SIZE:
        cxBlock = LOWORD(lParam) / DIVISION;
        cyBlock = HIWORD(lParam) / DIVISION;
        return 0;
    case WM_LBUTTONDOWN:
        x = LOWORD(lParam) / cxBlock;
        y = HIWORD(lParam) / cyBlock;

        if (x<DIVISION && y<DIVISION) {
            fState[x][y] ^= 1;
            rect.left = x*cxBlock;
            rect.top  = y*cyBlock;
            rect.right = (x+1) * cxBlock;
            rect.bottom = (y+1) * cyBlock;

            InvalidateRect(hwnd, &rect, FALSE);
        } else {
            MessageBeep(0);
        }
        return 0;
    case WM_PAINT:
        hdc = BeginPaint(hwnd, &ps);
        
        for (x=0; x<DIVISION; x++){
            for(y=0; y<DIVISION; y++) {
                Rectangle(hdc, x*cxBlock, y*cyBlock, (x+1)*cxBlock, (y+1)*cyBlock);
                if (fState[x][y]) {
                    MoveToEx(hdc, x*cxBlock, y*cyBlock, NULL);
                    LineTo(hdc, (x+1)*cxBlock, (y+1)*cyBlock);
                    MoveToEx(hdc, x*cxBlock, (y+1)*cyBlock, NULL);
                    LineTo(hdc, (x+1)*cxBlock, y*cyBlock);
                }
            }
        }
        EndPaint(hwnd, &ps);
        return 0;

    case WM_DESTROY:
        PostQuitMessage(0);
        return 0;
    }
    return DefWindowProc(hwnd, message, wParam, lParam);
}